Apparatus for electrospinning liquid polymer into nanoscale or submicron scale fibers

ABSTRACT

An apparatus for continuous needless electrospinning of a liquid polymer source into a nanoscale or submicron scale polymer fiber web includes an electrospinning enclosure, a wire drive system located external to the electrospinning enclosure and a plurality of continuous electrode wires. The electrospinning enclosure includes and electrospinning zone and one or more liquid polymer coating devices where liquid polymer is coated onto the plurality of continuous electrode wires. The plurality of continuous electrode wires are parallel to each other, engaged with the wire drive system, and extend through the electrospinning enclosure and the one or more liquid polymer coating devices located therein. High voltage is applied to the plurality of continuous electrode wires in the electrospinning zone to form nanoscale or submicron scale polymer fibers from the liquid polymer coated on the electrode wires.

FIELD OF THE DISCLOSURE

The present disclosure relates an apparatus and methods forelectrospinning liquid polymer into nanoscale or submicron scale fibers,and more particularly to electrospinning liquid polymer into nanoscaleor submicron scale fibers without the use of conventional nozzles orneedles.

BACKGROUND OF THE DISCLOSURE

Fibers in the nanoscale or submicron scale are useful in a variety ofapplications, including filtration, tissue engineering, protectiveclothing, composites, battery separators, energy storage, etc.Electrospinning is one of the methods used to generate high qualityfibers on this scale. While electrospinning is relatively easy to do,however, it has very low throughput and subsequently, a very highproduction cost. Therefore, it is not cost effective to electrospinnanoscale and/or submicron scale fibers in large quantities.Accordingly, other than for high-value applications, electrospinning ofnanofibers has been largely contained to academic research.

Production rates in current injection nozzle, needle-jet and spinningjet manufacturing processes typically range from about 0.05 grams perhour (g/hr) to about 0.15 g/hr per nozzle/jet. Several methods have beenstudied and/or used to improve the production rate. These methodsinclude gas-assisted electrospinning; the use of multi-nozzle systems;the use of nozzle-less/needleless systems; and increasing the totalnumber spinning jets. Each of these methods has its problems, however,resulting in maximum sustained production rates of no more than about 2kilograms per hour (kg/hr) per (commercially available) machine.Problems associated with nozzle/needle systems include: clogging of theinjection nozzle/needle orifice; difficulty optimizing the nozzle array;and difficulty maintaining uniform feed rate through each nozzle.Problems associated with nozzle-less/needleless systems include:inability to control solvent evaporation from the solution reservoir,resulting in solution concentration and viscosity variations; andpolymer layer coating build-up on the surface of the electrospinningelement resulting in a substantial decrease in the fiber spinning rate.

These and other shortcomings are addressed by aspects of the presentdisclosure.

BRIEF DESCRIPTION OF THE FIGURES

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various aspects discussed in the presentdocument.

FIG. 1 is a side view of a simplified electrospinning apparatusaccording to an aspect of the disclosure.

FIG. 2 is a side view of a liquid polymer coating device for applying alayer of liquid polymer onto a plurality of continuous electrode wiresaccording to an aspect of the disclosure.

FIG. 3 is a detail in section taken on the line A-A of FIG. 2.

FIG. 4A is a detail in section taken on the line B-B of FIG. 2.

FIG. 4B is a side view of an exemplary electrode wire cleaning assemblyaccording to an aspect of the disclosure.

FIG. 5 is a side view of a simplified diagram showing the travel pathfor the plurality of continuous electrode wires including theelectrospinning enclosure, wire drive system and wire tensioning system.

FIG. 6 is a detail in section taken on the line A-A of FIG. 5.

FIG. 7 is a detail in section taken on the line B-B of FIG. 6.

FIG. 8 is a schematic diagram showing auxiliary systems of anelectrospinning apparatus according to aspects of the disclosure.

FIG. 9 is a detailed schematic diagram of an electrospinning apparatusaccording to an aspect of the disclosure.

FIG. 10 is a partial schematic diagram of an electrospinning apparatusshowing Section A of FIG. 9.

FIG. 11 is a partial schematic diagram of an electrospinning apparatusshowing Section B of FIG. 9.

FIG. 12 is a partial schematic diagram of an electrospinning apparatusshowing Section C of FIG. 9.

FIG. 13 is a block diagram illustrating a method for continuousneedleless electrospinning of a liquid polymer source into a nanoscaleor submicron scale polymer fiber web according to an aspect of thedisclosure.

FIG. 14 is a block diagram illustrating a method for driving a pluralityof continuous electrode wires through an electrospinning apparatusaccording to an aspect of the disclosure.

FIG. 15 is a block diagram illustrating a method for collecting ananoscale or submicron scale polymer fiber web from an electrospinningenclosure according to an aspect of the disclosure.

FIG. 16 is a block diagram illustrating a method for operating anelectrospinning apparatus for continuous needleless electrospinning ananoscale or submicron scale polymer fiber web onto a substrate.

SUMMARY

Aspects of the disclosure relate to an apparatus for continuous needlesselectrospinning of a liquid polymer source into a nanoscale or submicronscale polymer fiber web, including:

a. an electrospinning enclosure including:

-   -   one or more liquid polymer coating devices;    -   an electrospinning zone including an electrically conductive        ground plate; and    -   a wire cleaning assembly;

b. a wire drive system located external to the electrospinningenclosure;

c. a plurality of continuous electrode wires, the plurality ofcontinuous electrode wires being parallel to each other, engaged withthe wire drive system, and extending through the electrospinningenclosure and one or more liquid polymer coating devices locatedtherein;

d. a substrate conveyor system located external to the electrospinningenclosure; and

e. one or more high voltage power supply units.

The one or more liquid polymer coating devices coat a layer of liquidpolymer onto a surface of the plurality of continuous electrode wires.The one or more high voltage power supply units apply high voltage tothe plurality of continuous electrode wires and generate an electricalfield between the plurality of continuous electrode wires and theelectrically conductive ground plate in the electrospinning zone,forming nanoscale or submicron scale polymer fibers from the liquidpolymer coated onto the surface of the plurality of continuous electrodewires. The wire cleaning assembly includes a solvent for cleaningresidual liquid polymer from the plurality of continuous electrodewires. The substrate conveyor system drives the substrate through theelectrospinning enclosure and collects the nanoscale or submicron scalepolymer fibers on the substrate as a polymer fiber web.

Aspects of the disclosure further relate to methods for continuousneedleless electrospinning of a liquid polymer source into a nanoscaleor submicron scale polymer fiber web, including:

driving a plurality of continuous electrode wires through anelectrospinning enclosure comprising at least one liquid polymer coatingdevice and an electrospinning zone with a wire drive system locatedexternal to the electrospinning enclosure;

driving a substrate through the electrospinning enclosure and theelectrospinning zone substantially parallel to the plurality ofcontinuous electrode wires with a substrate conveyor system locatedexternal to the electrospinning enclosure;

coating a layer of liquid polymer onto a surface of the plurality ofcontinuous electrode wires in the at least one liquid polymer coatingdevice;

forming, in the electrospinning zone, nanoscale or submicron scalepolymer fibers from the liquid polymer coated onto the surface of theplurality of continuous electrode wires;

collecting the nanoscale or submicron scale polymer fibers on thesubstrate as a polymer fiber web; and

removing residual polymer from the surface of the plurality ofcontinuous electrode wires using a wire cleaning assembly located withinthe electrospinning enclosure.

DETAILED DESCRIPTION

The present disclosure can be understood more readily by reference tothe following detailed description of the disclosure and the Examplesincluded therein. In various aspects, the present disclosure pertains toapparatus and methods for electrospinning a polymer fiber web onto asubstrate and collecting it onto a roller. The apparatus and methodsdescribed herein allow the production of nanoscale or submicron scalefibers at a much higher throughput and production intensity—and withmuch lower capital investment and production cost—relative to that bythe current available and known electrospinning methods.

Before the present compounds, compositions, articles, systems, devices,and/or methods are disclosed and described, it is to be understood that,unless otherwise specified, they are not limited to a specific polymermaterial, or to a particular status of polymer material (i.e., melt orsolution), or to a particular type of solvent used to prepare a polymersolution, or to particular operating conditions (e.g., polymer wt % inthe solution, additives in a polymer solution, temperature, voltage,distance of the electric field, etc.), or to particular apparatusdimensions and materials of construction (e.g., the composition of theelectrode wires, the number of continuous electrode wires, the length ofthe electrode wires, the distance between parallel electrode wires, thenumber of polymer coating devices in one electrode wire pass, thedistance between two liquid polymer coating devices, etc.), and as suchthese parameters can vary. It is also to be understood that theterminology used herein is for the purpose of describing particularaspects only and is not intended to be limiting.

Various combinations of elements of this disclosure are encompassed bythis disclosure, e.g., combinations of elements from dependent claimsthat depend upon the same independent claim.

Moreover, it is to be understood that unless otherwise expressly stated,it is in no way intended that any method set forth herein be construedas requiring that its steps be performed in a specific order.Accordingly, where a method claim does not actually recite an order tobe followed by its steps or it is not otherwise specifically stated inthe claims or descriptions that the steps are to be limited to aspecific order, it is no way intended that an order be inferred, in anyrespect. This holds for any possible non-express basis forinterpretation, including: matters of logic with respect to arrangementof steps or operational flow; plain meaning derived from grammaticalorganization or punctuation; and the number or type of aspects describedin the specification.

All publications mentioned herein are incorporated herein by referenceto disclose and describe the methods and/or materials in connection withwhich the publications are cited.

Electrospinning Apparatus

With reference to FIGS. 1 to 12, aspects of the disclosure relate to anapparatus 100 for electrospinning a polymer fiber web 110 onto asubstrate 120. A simplified schematic diagram of the apparatus 100 isillustrated in FIG. 1. Particular components of the apparatus include anelectrospinning enclosure 300, at least one liquid polymer coatingdevice 400, a wire drive system 600, a wire tensioning system 700, anelectrically conductive ground plate 800 and at least one high voltagepower supply unit 820 that applies a high voltage to the plurality ofcontinuous electrode wires 1000. A substrate 120 is unrolled from asubstrate supply roller 200 and driven through the electrospinningenclosure. A plurality of continuous electrode wires 1000 are driventhrough the electrospinning enclosure generally parallel to the face ofthe moving substrate 120 by the wire drive system 600 and wiretensioning system 700. The moving directions of the plurality ofcontinuous electrode wires 1000 and substrate 120 could either beco-current or counter-current. The plurality of continuous electrodewires 1000 are coated with a layer of liquid polymer in each of the atleast one liquid polymer coating devices 400, and the voltage differencebetween the high voltage applied to the plurality of continuouselectrode wires 1000 by the at least one high voltage power supply unit820 and the electrically conductive ground plate 800 causes many liquidTaylor Cone jets 840 to erupt from the surface of the plurality ofcontinuous electrode wires 1000, contact the substrate 120, and form apolymer fiber web 110 on the substrate 120. The polymer fiber web 110and substrate 120 exit the electrospinning enclosure 300 and arecollected by, e.g., winding them onto a combination roller 210 (as shownin FIG. 1), or in other aspects by separating the polymer fiber web 110from the substrate 120 and winding them onto separate fiber web rollersas described herein. A wire cleaning assembly 500 removes excess liquidpolymer as well as any solidified polymer from the surface of theplurality of continuous electrode wires 1000. The components andoperation of the apparatus 100 are described in further detail below.

The electrospinning enclosure 300 is an enclosed housing to contain theelectrospinning process and minimize the release of potential harmfulsubstances to the working environment. The electrospinning enclosure300—except for minimally sized apertures that allow the plurality ofcontinuous electrode wires 1000 to pass through the electrospinningenclosure 300 and narrow apertures that allow the substrate 120 (andpolymer fiber web 110 formed thereon) to pass into and out of theelectrospinning enclosure 300—is substantially enclosed and operatedbelow atmospheric pressure. Vapors that are generated in theelectrospinning process are contained inside the electrospinningenclosure 300 and subsequently collected in a vapor collection andsolvent recovery system 1600 as described in further detail herein. Insome aspects the electrospinning enclosure 300 is operated at a negativepressure relative to atmospheric pressure so that atmosphere/airproximate the electrospinning enclosure 300 is drawn into theelectrospinning enclosure 300 and collected by the vapor collection andsolvent recovery system 1600, which prevents potentially harmful vaporsin the electrospinning enclosure 300 from escaping to the atmosphere.The plurality of continuous electrode wires 1000 are driven into andthen out of the electrospinning enclosure 300 through apertures whosediameter is slightly larger than the diameter of the electrode wire usedand, as further described herein, are coated with a layer of liquidpolymer which provides the polymer source for the fibers in theelectrospun polymer fiber web 110.

The electrospinning enclosure 300 includes at least one liquid polymercoating device 400. The at least one liquid polymer coating device 400provides the liquid polymer source to coat the plurality of continuouselectrode wires 1000. In exemplary aspects the at least one liquidpolymer coating device 400 includes a liquid polymer coating manifold410 and a liquid polymer overflow reservoir 420.

The liquid polymer coating manifold 410 includes a plurality of wireinlet apertures 430 and a plurality of wire outlet apertures 440corresponding to the number of wire inlet apertures 430. The wire inletapertures 430 and wire outlet apertures may in some aspects have aportion that extend distally from the outside surface of the liquidpolymer coating manifold 410 for some length “L”, or they may have azero length L, in which case the thickness of the apertures correspondsto the thickness of the liquid polymer coating manifold. The diameterand length of the apertures may vary depending on the level of liquidpolymer overflow to be controlled. Liquid polymer is provided to theliquid polymer coating manifold 410 by a liquid polymer recycle and feedsystem 1200 through a liquid polymer supply port 450. The liquid polymerrecycle and feed system 1200 is described in further detail below. Insome aspects of operation, which is explained more fully herein, each ofthe plurality of continuous electrode wires 1000 is driven, in acontinuous loop, into the at least one liquid polymer coating device400, through a wire inlet aperture 430, and into the liquid polymercoating manifold 410 where it is coated with a layer of liquid polymer.Each coated continuous electrode wire 1000 then exits the liquid polymercoating manifold 410 through the wire outlet aperture 440 correspondingto its wire inlet aperture 430 (with which it is aligned) and exits theliquid polymer coating device 400.

The liquid polymer overflow reservoir 420 receives liquid polymeroverflow from the liquid polymer coating manifold 410 and any liquidpolymer that drips from the plurality of continuous electrode wires 1000exiting the liquid polymer coating manifold 410. As the liquid polymeroverflow reservoir 420 fills, a liquid polymer recirculation port 455recirculates the liquid polymer collected in the reservoir to the liquidpolymer recycle and feed system 1200. In some aspects the liquid polymerrecirculation port 455 recirculates liquid polymer to the liquid polymerrecycle and feed system 1200 by gravity flow.

The liquid polymer described herein may be any polymer suitable for usein electrospinning applications, and includes naturally occurring andsynthetic polymers in either a pure melt liquid state or a liquidsolution formed by dissolving the polymer into a pure solvent or asolvent mixture. Moreover, the liquid polymer could include one or morepolymers mixed together. Exemplary naturally occurring polymers suitablefor use in aspects of the disclosure include, but are not limited to,proteins, celluloses, lignin, collagen, DNA, and rubber. Exemplarysynthetic polymers suitable for use in aspects of the disclosureinclude, but are not limited to, polyamide, polyurethane,polybenzimidazole, polycarbonate, polyacrylonitrile, polyvinyl alcohol,polylactic acid, polyethylene-co-vinyl acetate, polymethacrylate,polyethylene oxide, polyaniline, polystyrene, polyvinylphenol,polyvinylchloride, polyetherimide, polyaramid, and synthetic rubber. Insome aspects one or more different kinds of polymer sources may beformed into a single polymer fiber web 110 with different fiber layers.For example, in a system including a plurality of liquid polymer coatingdevices 400, each of the liquid polymer coating devices 400 may besupplied with a different source of liquid polymer so that the polymerfiber web 110 would thus include multiple polymers having multiplelayers on the substrate 120.

The wire drive system 600 moves the plurality of continuous electrodewires 1000 through the electrospinning enclosure 300. In certain aspectsthe wire drive system includes a master wire drive drum 610 and a slavewire drive drum 620 that pulls the plurality of continuous electrodewires 1000. The driving force of the master wire drive drum 610 isdirectly coming from a power supply unit, such as variable frequencydrive (VFD) while the driving force of the slave wire drive drum 620 iscoming from the master wire drive drum 610. One particular advantage ofa master and slave wire drive drum arrangement is a substantial increasein the amount of pulling force that can be passed to each of thecontinuous electrode wires without slipping or skidding between thewires and the drums.

The master wire drive drum 610 includes a master gear plate 630 and theslave wire drive drum 620 includes a slave gear plate 640 coupled to themaster gear plate 630 so that when the master wire drive drum 610rotates the slave wire drive drum 620 rotates in the opposite direction.The master wire drive drum 610 is coupled to a motor-driven shaft 650that rotates the master wire drive drum 610. In some aspects a variablespeed motor drives the master wire drive drum 610. The speed of themaster wire drive drum 610 may be varied in some aspects to drive theplurality of continuous electrode wires 1000 at a speed of from about 1meter per minute (m/min) to about 200 m/min. In certain aspects a fixedspeed motor could drive the master wire drive drum 610.

The slave wire drive drum 620 is coupled to a free-rotating shaft 660that allows it to rotate freely in response to rotation of the masterwire drive drum 610. In another aspect the slave wire drive drum 620 maybe driven by the master wire drive drum 610 by a chain rather than bycoupled gear plates (630, 640) such as those described herein.

As illustrated in FIG. 6, each of the master wire drive drum and slavewire drive drum include a plurality of wire guides 670 to separate theplurality of continuous electrode wires 1000. Each of the plurality ofwire guides includes a channel or groove to guide one of the pluralityof electrode wires 1000. As shown in FIG. 5 (for only one wire), thecontinuous electrode wire 1000 is pulled by the master wire drive drum610 and the slave wire drive drum 620. The continuous electrode wire1000 may be guided by a wire guide 670 on each of these wire drums. Fromthe slave wire drive drum 620, the continuous electrode wire may belooped through the wire tensioning system 700.

The wire tensioning system 700 provides a requisite amount of tension tothe plurality of continuous electrode wires 1000. In certain aspects thewire tensioning system independently tensions each of the plurality ofcontinuous electrode wires 1000. This could be accomplished by havingeach of the continuous electrode wires 1000 guided by an independentwire tensioner 710 that provides independent tension to the continuouselectrode wire. FIG. 5 provides an example for one wire and shows onewire tensioner 710; it would be recognized that in some aspects eachcontinuous electrode wire 1000 would have its own wire tensioner 710.Thus, an apparatus including 250 wires would include 250 individualtensioners. In certain aspects, the individual tensioners may beseparated into groups that are installed in different locations toaddress issues relating to installation space limitations. For example,it could be difficult to install the exemplary 250 individual tensionersin a single row where it is desirable to space the continuous electrodewires a short distance apart from one another (e.g., 5 millimeters (mm)apart, or 10 mm apart, or 15 mm apart, or 20 mm apart). Thus, in oneaspect the continuous electrode wires may be separated into 5 groups:with Group 1 including the tensioners for wires 1, 6, 11, 16, . . . and246; Group 2 including the tensioners for wires 2, 7, 12, 17, . . . and247; Group 3 including the tensioners for wires 3, 8, 13, 18, . . . and248; Group 4 including the tensioners for wires 4, 9, 14, 19, . . . and249; and Group 5 including the tensioners for wires 5, 10, 15, 20, . . .and 250. In this manner, the available distance between tensioners foreach wire increases to 25 mm.

The plurality of continuous electrode wires 1000 may be any suitablewire type, including but not limited to braided, twisted, piano anddrawn. It may be desirable to select a wire that provides a relativelyhigh surface area so that more liquid polymer can coat the surface ofthe wire and be available for electrospinning, although a higher surfacewire could provide more surfaces for retention of residual unreactedpolymer, which could present a contamination/cleaning concern.

The apparatus 100 and associated components described herein—includingbut not limited to the wire drive system 600; wire tensioning system 700with individual wire tensioners 710; and electrospinning enclosure 300containing at least one liquid polymer coating device 400 including aliquid polymer coating manifold 410 having a plurality of wire inletapertures 430 and corresponding wire outlet apertures 440—allows dozensor even hundreds of continuous electrode wires 1000 to be driven throughthe electrospinning enclosure 300 where they can be coated with liquidpolymer and be used in an electrospinning process. Moreover, theseplurality of (dozens/hundreds of) continuous electrode wires 1000 arecontinuously cycling through the electrospinning enclosure 300 in anendless loop, so the electrospinning process for forming the polymerfiber web 110 can be carried out at a much greater capacity (severalorders of magnitude greater) than currently known electrospinningprocesses.

The apparatus includes at least one high voltage power supply unit 820that provides the requisite electric field strength for theelectrospinning process. Each of the at least one high voltage powersupply units 820 has a negative voltage source and a positive voltagesource. In general, the negative voltage source is wired and connectedto an electrically conductive ground plate 800 located inside theelectrospinning enclosure 300 and proximate a first side 810 of thesubstrate 120 while the positive voltage source is wired and connectedto at least one electrically conductive freely rotating axle 850 incontact with the plurality of continuous electrode wires 1000, which asshown in FIGS. 1 and 10 are located proximate a second side 830 of thesubstrate 120. In some aspects the at least one electrically conductivefreely rotating axle 850 includes a plurality of grooves (e.g., V-shapedgrooves) evenly distributed on its surface. Each of the grooves receivesone of the continuous electrode wires 1000. Good contact between thegroove and electrode wire is maintained by adjusting the correspondingwire tensioner 710 so that the positive electric voltage from the atleast one high voltage power supply unit 820 is passed on to each of theelectrode wires 1000. During operation, the electrically conductivefreely rotating axle 850 rotates freely as the electrode wires 1000move. In some aspects, the positive and negative sources of the at leastone high voltage power supply unit 820 may be switched between theelectrically conductive ground plate 800 and the continuous electrodewires 1000. In such aspects a negative voltage electrospinning processis contemplated.

The at least one high voltage power supply unit 820, shown in FIG. 1 asexternal to the electrospinning enclosure 300, applies a voltagedifference between the electrically conductive ground plate 800 and theplurality of continuous electrode wires 1000. During operation, thepositive voltage applied to the liquid polymer-coated continuouselectrode wires 1000 passing across the electrically conductive groundplate 800 in the electrospinning zone Z of the electrospinning enclosure300 resulted in an electric field that causes the liquid polymer on thecontinuous electrode wire 1000 to become charged, resulting in chargedliquid Taylor Cone jets 840 erupting from the surface of the continuouselectrode wires 1000 towards the negative voltage source of theconductive ground plate 800. The liquid Taylor Cone jets 840 elongateand partially dry in flight, forming a polymer fiber having ananometer-scale or submicron scale diameter. The fibers contact thesubstrate 120 and are collected thereon, which is also moving throughthe electrospinning enclosure 300 generally parallel to and in eitherthe same or opposite direction as the plurality of continuous electrodewires 1000. As this process is repeated through the length of theconductive ground plate 800, which may be referred to as anelectrospinning zone Z, a polymer fiber web 110 is formed on thesubstrate 120. While the polymer fiber is described herein as having ananometer-scale diameter or submicron scale diameter and these fibersare commonly referred to as nanofibers or submicron fibers, it will berecognized that the fibers produced by the apparatus and methodsdescribed herein need not be nanofiber-sized or submicron-sized and thatthe process conditions may be modified so as to form fibers having othersizes.

While the at least one high voltage power supply unit 820 is shown inFIG. 1 as external to the electrospinning enclosure 300, it need not be.It could be located within the electrospinning enclosure 300 if desired.

With specific reference to FIG. 3, in certain aspects one or more of thewire inlet apertures 430 and wire outlet apertures 440 include acapillary tube 460 disposed between the wire inlet aperture 430/wireoutlet aperture 440 and its respective continuous electrode wire 1000.As illustrated, the capillary tube 460 may extend outward from theliquid polymer coating manifold 410 for a length L, and may be sized sothat it has an inner diameter that is slightly larger than the diameterof the continuous electrode wire 1000 passing therethrough, resulting ina small gap 470. The inner diameter of the capillary tube 460 is sizedso as to be large enough to allow the continuous electrode wire 1000 topass through the liquid polymer coating manifold 410 with a minimumamount of friction but small enough to prevent excessive loss of liquidpolymer from the liquid polymer coating manifold 410. Further, thelength L of the capillary tube provides liquid backpressure in theliquid polymer coating manifold so as to further minimize loss of liquidpolymer from the capillary tube(s) 460. Liquid polymer that exits thecapillary tube 460 (and its respective wire inlet aperture/wire outletaperture) drains to the liquid polymer overflow reservoir 420 asdescribed herein.

In some aspects the liquid polymer coating device 400 may furtherinclude a liquid polymer overflow port 480. The liquid polymer overflowport 480 may provide a further source for liquid polymer to overflowinto the liquid polymer overflow reservoir 420 as described herein. Insome aspects the liquid polymer overflow port 480 may be configured toprovide a constant overflow amount to ensure that the liquid polymer inthe liquid polymer coating device 400 is continuously moving and has arelatively constant temperature.

In certain aspects the liquid polymer coating device 400 may include atleast one set of wire positioning pulleys 490. The at least one set ofwire positioning pulleys 490 may be located proximate the plurality ofwire inlet apertures 430 as shown in FIG. 2, and may function to guidethe plurality of continuous electrode wires 1000 into the plurality ofwire inlet apertures 430 of the liquid polymer coating manifold 410.

The apparatus 100 may in certain aspects include a wire cleaningassembly 500. The wire cleaning assembly 500 may be included to removeresidual liquid polymer or other electrospinning residues from thesurface of the plurality of continuous electrode wires 1000. The wirecleaning assembly 500 may include, but does not have to include, similarfeatures as the liquid polymer coating device 400 described herein. Anexemplary wire cleaning assembly 500 is illustrated in FIG. 4B andincludes a solvent coating manifold 510 that includes a number ofsolvent manifold wire inlet apertures 530 and solvent manifold wireoutlet apertures 540 corresponding to the number of continuous electrodewires 1000. The solvent coating manifold 510 may also include a solventoverflow reservoir 520 that receives overflow solvent from the solventmanifold wire inlet apertures 530 and solvent manifold wire outletapertures 540. Fresh solvent may be provided to the wire cleaningassembly 500, and if included the solvent coating manifold 510, by wayof a solvent coating port 550 associated with a solvent supply stream1420. Excess solvent collected in the solvent overflow reservoir 520 maybe returned to a solvent storage and supply system 1400 by way of asolvent recirculation port 555 associated with a solvent recirculationstream 1430. The solvent coating manifold 510 may thus operate in thesame manner as the liquid polymer coating manifold 410 but provides asolvent solution to the plurality of continuous electrode wires 1000 toremove residual liquid polymer or other electrospinning residue from thecontinuous electrode wires 1000. The solvent can be either the same kindused to prepare the liquid polymer (e.g., the polymer solution) or anyother suitable solvent. In some aspects the solvent recirculation port555 recirculates solvent to the solvent storage and supply system 1400by gravity flow.

The wire cleaning assembly 500 may be located within the electrospinningenclosure 300 as shown in FIG. 5 or outside the electrospinningenclosure 300 (not shown), although it will be recognized that in eithercase the wire cleaning assembly 500 will typically be located after, ordownstream of, the electrospinning zone Z. As used herein, “upstream”and its counterpart term “downstream” relate to the location of onecomponent relative to another with respect to the direction of travel ofthe plurality of continuous electrode wires 1000 during operation of theapparatus. In some aspects, as the continuous electrode wires 1000 exitthe wire cleaning assembly 500 and before they exit the electrospinningenclosure 300, any retained solvent on the surface of the wires may beevaporated in a solvent drying step, which prevents the continuouselectrode wires 1000 from carrying potentially harmful solvent to theenvironment.

In some aspects the apparatus 100 further includes an electricconductive resistance measuring system 560. The resistance measuringsystem includes a device such as an ohm meter 570 configured to measureresistance of one or more of the plurality of continuous electrode wires1000 at both an upstream contact point 580 (i.e., prior to liquidpolymer coating) and at a downstream contact point 590 (i.e., followingthe electrospinning zone Z and/or the wire cleaning assembly 500). Ameasured resistance may indicate that one or more of the plurality ofcontinuous electrode wires 1000 exiting the electrospinning enclosure300 may contain solid polymer on their corresponding surfaces and mayneed further cleaning through a harsher cleaning method such as with awire scrubber 1900 or other cleaning system. In particular aspects theresistance measuring system is configured to measure each of theplurality of continuous electrode wires 1000 at the upstream contactpoint 580 and at the downstream contact point 590 over a particular timeinterval (e.g., every 5 milliseconds (ms)).

With reference to FIG. 8 and as explained above, the apparatus mayinclude a liquid polymer recycle and feed system 1200. The liquidpolymer recycle and feed system 1200 provides liquid polymer to each ofthe at least one liquid polymer coating devices 400 by way of the liquidpolymer supply port 450 of the liquid polymer coating manifold 410provided in each of the liquid polymer coating devices 400. In addition,the liquid polymer recycle and feed system 1200 receives liquid polymeroverflow received from each of the at least one liquid polymer coatingdevices 400 by way of the liquid polymer recirculation port 455 providedtherein. The liquid polymer recycle and feed system 1200 includes arecycle and feed tank 1210 for receiving recycled liquid polymer fromeach of the at least one liquid polymer coating devices 400 anddelivering liquid polymer feed thereto, a liquid polymer circulation andsupply pump 1220 that pumps liquid polymer to each of the at least oneliquid polymer coating devices 400 (through, e.g., a liquid polymerdistribution manifold (not illustrated)), and a liquid polymer heatexchanger 1230 that operates to maintain a desired liquid polymertemperature. It should be noted that the schematic diagram in FIG. 8illustrates various pumps (“M”), flow meters (“F”), valves (“V”),composition analyzers/transmitters (“CA”) and heat exchangers/coolers(“HC”), the proper selection and operation of which is known to those inthe art and not specifically described herein.

The liquid polymer recycle and feed system 1200 receives liquid polymerfrom a liquid polymer preparation system 1300 by way of a liquid polymercharging stream 1305. The liquid polymer recycle and feed system 1200operates to provide the liquid polymer used for the electrospinningprocess at the requisite concentration and temperature. The liquidpolymer preparation system 1300 includes a liquid polymer preparationtank 1310 which in some aspects includes an agitator and a polymerstorage and charging unit 1320. In some aspects the liquid polymerpreparation system 1300 operates in a batch process and includes stepsof: (a) receiving into the liquid polymer preparation tank 1310 apre-determined amount of solvent from the solvent storage and supplysystem 1400 by way of a solvent charging stream 1350; (b) receiving intothe liquid polymer preparation tank 1310 a pre-determined amount ofpolymer from the polymer storage and charging unit 1320; (c) mixing andheating the solvent and polymer in the liquid polymer preparation tankto a pre-determined temperature until the solid polymer dissolvescompletely in the solvent; and (d) transferring the prepared polymersolution batch to the recycle and feed tank 1210. In some aspects theliquid polymer preparation tank may include agitation and heatingfeatures to facilitate preparation of the liquid polymer. As shown inFIG. 8, the liquid polymer preparation system may also include incertain aspects a liquid polymer preparation transfer pump 1330 thatcirculates the liquid polymer in the liquid polymer preparation tank1310 through a polymer preparation heat exchanger 1340 and, at thecompletion of the batch, transfer the liquid polymer from the polymerpreparation tank 1310 to the recycle and feed tank 1210 by way of theliquid polymer charging stream 1305.

In certain aspects the apparatus 100 may also include a solvent storageand supply system 1400. The solvent storage and supply system 1400operates to store and supply solvent to the liquid polymer preparationsystem 1300 and to the wire cleaning assembly 500. In some aspects theprimary source of solvent for the solvent storage and supply system isthe solvent recovered in the vapor collection and solvent recoverysystem 1600, as explained in further detail below. In such aspects freshmake-up solvent could be added from another source (not illustrated) tobalance any solvent lost during operation of the wire cleaning assembly500 and other solvent handling. The solvent storage and supply system1400 includes a solvent storage tank 1410. Solvent from the solventstorage tank 1410 is provided to the wire cleaning assembly 500 by wayof a solvent supply stream 1420 and receives overflow solvent from thewire cleaning assembly by way of a solvent recirculation stream 1430. Inaddition, solvent could be provided to the liquid polymer recycle andfeed system 1200 by way of a liquid polymer dilution stream 1440 if itis necessary to dilute the concentration of the liquid polymer in theliquid polymer recycle and feed system 1200. A solvent supply pump 1450pumps the solvent to the wire cleaning assembly 500, the liquid polymerrecycle and feed system 1200 and the liquid polymer preparation system1300.

In further aspects the apparatus 100 includes a vapor collection andsolvent recovery system 1600, which in some aspects includes severalsubsystems whose operation and functions are described in further detailbelow.

In some aspects the vapor collection and solvent recovery system 1600provides a requisite level of vacuum to the electrospinning enclosure300 so that atmosphere/air proximate the electrospinning enclosure 300is drawn into the electrospinning enclosure 300, which preventspotentially harmful vapors in the electrospinning enclosure 300 fromescaping to the environment. In certain aspects, and as shown in FIG. 8,the vapor collection and solvent recovery system includes five blowers(blower #1 1505, blower #2 1510, blower #3 1515, blower #4 1520 andblower #5 1525) for drawing vapor and gas from the electrospinningenclosure 300 into the vapor collection and solvent recovery system1600. Blower #1 1505 draws ambient air into the electrospinningenclosure 300 at various entry points (ambient air entry points #11610A, #2 1610B and #3 1610C), including openings where the plurality ofcontinuous electrode wires 1000 enter and exit the electrospinningenclosure 300 (emission control box 1800A), where the substrate 120enters the electrospinning enclosure 300 (emission control box 1800B)and where the substrate 120 exits the electrospinning enclosure 300(emission control box 1800C). Ambient air and some polymer and solvent(via emission control box exhaust streams 1605A, 1605B, and 1605C) aredrawn through blower #1 1505, collected and ultimately disposed of in anincinerator 1620 to remove harmful residual vapors. The emission controlbox exhaust streams may in some aspects be attached or coupled to theemission control box by known mechanical attachment methods. In someaspects blower #1 1505 operates emission control boxes 1800A, 1800B and1800C at a vacuum of about −2″ water column gauge (WCG) to about −10″WCG.

The output of the incinerator 1620 may be vented to the atmosphere. Incertain aspects blower #3 1515 collects solvent vapor generated anddraft gas (if used) by way of the solvent vapor stream 1630 which has arelatively low temperature and is rich in solvent vapor. Blower #2 1510,on the other hand, collects the vapor generated from fiber drying andhot drying gas utilized for the fiber drying by the way of the hot gasexhaust stream 1605D which has relatively high temperature and low vaporconcentration. The vapor/gas from blower #2 1510 passes heat exchanger#1 1540 to exchange the heat with the vent gas stream from the solventcondenser 1640 by way of blower #5 1525. After heat exchanger #1, thestream from the outlet of blower #2 1510 (having a decreasedtemperature) merges with the solvent vapor stream 1630 from the outletof blower #3 1515. This combined vapor/gas stream enters a venturi mixer1565 and the solvent condenser 1640. The venturi mixer 1565 mixes thevapor/gas stream and a cold liquid circulation stream from pump #1 1535so that the vapor/gas temperature is further cooled to approximately theoperating temperature of the solvent liquid inside the solvent condenser1640. As a result, most of the solvent vapor in the vapor/gas stream iscondensed into a liquid. The heat released by the condensation of thevapor is absorbed by the cold solvent liquid circulation stream enteringthe venturi mixer and subsequently such heat is removed by heatexchanger #2 1545 using a cooling medium, such as but not limited tocooling water and chilled water. Any solvent vapor not condensed throughthe operation of venturi mixer 1565 will be further condensed when thevent gas out of solvent condenser 1640 passes through heat exchanger #51560. Recovered liquid solvent inside the solvent condenser 1640 isreturned to the solvent storage and supply system 1400 by way of asolvent condensate stream 1650. In some aspects the rate of return maybe controlled by the liquid level inside the solvent condenser 1640.

After heat exchanger #5 1560, the vent gas has a lower vapor content inthe gas. The vent gas stream may be split into two separate streams, oneto blower #5 1525 and another to blower #4 1520. The vent gas out ofblower #5 1525 is further split into two streams, one to incinerator1620 and another to heat exchanger #1 1540. The flow rate of the ventstream to the incinerator 1620 may be controlled based on the requiredgas purge amount, which may be calculated based on the deviation of themeasured oxygen concentrations in the solvent vapor stream 1630 and hotgas supply stream 1670 from a pre-set value. In some aspects the pre-setvalue is nominally 20-30% of the oxygen concentration under which thesolvent vapor has the potential to be ignited. As the deviationincreases, more vent stream gas is purged to the incinerator 1620 andvice versa. The temperature of the other vent stream from blower #5 1525increases after it passes through heat exchanger #2 1545. This heatedvent gas is returned to the electrospinning enclosure 300 and reused asdraft gas for the electrospinning process. The vent stream to blower #41520 is further split into two separate streams, one to heat exchanger#3 1550 and another to an adsorption bed 1660. The temperature of thevent stream out of heat exchanger #3 1550 is increased to a pre-setvalue that in some aspects is the temperature for the primary drying gasused for drying the fiber web inside the electrospinning enclosure 300.

Aspects of the apparatus 100 described herein provide at least anadditional advantage over current electrospinning processes by allowingelectrospinning of toxic or flammable polymers, as the electrospinningenclosure, which is operated below atmospheric pressure, prevents toxicand/or flammable vapors from escaping into the atmosphere/workingenvironment. These vapors are collected and safely processed asdiscussed herein. More particularly, in some aspects the electrospinningenclosure 300 includes one or more oxygen sensors to measure and/ormonitor the oxygen content in the enclosure. If the detected oxygencontent is higher than a pre-set low value, more vent gas from blower #51525 is sent to the incinerator 1620 and fresh inert gas (such as butnot limited to nitrogen) may be charged into the electrospinningenclosure 300 until the oxygen content inside the electrospinningenclosure 300 drops below the pre-set low value. In further aspects, ifthe detected oxygen content becomes higher than a pre-set high value,the high voltage power supply unit 820 could be automatically shut downas a safety feature. The safety feature could include, e.g., switchingthe contacts of the high voltage power supply unit 820 to a groundingsystem and/or charging a large quantity of fresh nitrogen into theelectrospinning enclosure 300. In this manner, these features mayregulate the oxygen concentration inside the electrospinning enclosurein a range from a pre-set-low value to a pre-set-high value, which insome aspects is approximately 30% of the oxygen concentration underwhich the gas/vapor mixture maybe ignite with an ignition source.

As shown in FIG. 8, the adsorption bed 1660 in some aspects is a carbonadsorption bed which removes residual solvent vapor from blower #4 1520to a predetermined low level suitable for the secondary drying gas usedfor drying the fiber web inside the electrospinning enclosure 300. Therequired temperature of the secondary drying gas may be obtained bypassing the gas stream from the adsorption bed 1660 through heatexchanger #4 1555. This heated gas, which has a very low solvent vaporcontent, is sent into the electrospinning enclosure 300 and is used asthe source of drying gas. The electrospinning enclosure 300 may includeone or more pressure sensors for monitoring the pressure therein. Asdiscussed, the operating pressure in the electrospinning enclosure ismaintained at a pressure lower than atmospheric pressure, which iscontrolled by sending the required amount of fresh make-up gas to thegas stream prior to the heat exchanger 1555. For example, if themeasured pressure inside the electrospinning enclosure 300 is less thana pre-set value, then more fresh make-up gas will be charged into thesystem and vice versa. On the other hand, if the measured pressureinside the electrospinning enclosure 300 is higher than the pre-setvalue (even with zero fresh make-up gas flow) then the vent gas amountfrom blower #5 1525 to the incinerator 1620 may be correspondinglyincreased. In this manner, the operating pressure inside theelectrospinning enclosure may be controlled in a range from apre-set-low value to a pre-set high value.

FIGS. 9-12 provide a detailed schematic diagram of the apparatus 100that is more generally illustrated in FIG. 1. The overall apparatus isshown in FIG. 9, and is divided into three sections as shown. Section Ais illustrated in FIG. 10, Section B is illustrated in FIG. 11, andSection C is illustrated in FIG. 12. In certain aspects, the apparatus100 may include other features in addition to one or more of thecomponents described above.

Draft gas may be blown onto the plurality of continuous electrode wires1000 in the electrospinning enclosure 300 by way of a draft gas supplysystem including a draft gas source 1710 (shown on FIG. 11) whichincludes the hot gas supply stream 1670 shown in FIG. 8 and a draft gasdistribution manifold 1720. The draft gas distribution manifold 1720 maydistribute the draft gas to the plurality of continuous electrode wires1000 through a series of vents, nozzles or other suitable openings. Thedraft gas supply system provides an upward force on the liquid TaylorCone jets 840 erupting from the surface of the plurality of continuouselectrode wires 1000 to help ensure that that the polymer fibers formedfrom the liquid Taylor Cone jets 840 reach the surface of the substrate120. In some aspects one or both of the temperature (through heatexchanger #1 1540) and the flowrate (through the control valve aboveheat exchanger #1 1540) of the draft gas may be adjusted for desirableperformance. Draft gas may be removed by way of an exhaust manifold 1680by blower #3 1515 (shown in FIG. 8) described herein.

The polymer fiber web 110 formed on the substrate 120 may not becompletely dry when formed and may include residual solvent. In someaspects of the disclosure two drying steps, a primary drying step and asecondary drying step, may be used to dry the polymer fiber web 110. Ineach drying step hot gas is used as the drying medium. The hot gasexiting heat exchanger #3 1550 is used as the drying medium in theprimary drying step (primary drying gas) while hot gas exiting heatexchanger #4 1555 is used as the drying medium in the secondary dryingstep (secondary drying gas). The secondary drying gas has a relativelylower solvent vapor content and higher temperature than the primarydrying gas.

The primary drying gas enters a primary drying region through a primarydistribution manifold 1690A (see FIG. 11) while the secondary drying gasenters the secondary drying region through a secondary distributionmanifold 1690B (FIG. 10). Both the primary drying gas and secondarydrying gas exit the electrospinning enclosure 300 through hot gasexhaust stream 1605D by blower #2 1510 as shown in FIG. 8. The primaryand secondary distribution manifolds 1690A and 1690B may distribute thehot gases to the substrate 120/polymer fiber web 110 through a series ofvents, nozzles or other suitable openings. In some aspects, thetemperature and flow rate of the primary drying gas may be adjusted andcontrolled by heat exchanger #3 1550 and its associated control valve.In the same manner, the temperature and flow rate of the secondarydrying gas may be adjusted and controlled by heat exchanger #4 1555 andits associated control valve.

As described herein, the apparatus 100 includes a substrate conveyorsystem 150 for moving the substrate through the electrospinningenclosure 300. In some aspects the substrate 120 and polymer fiber web110 formed thereon may exit the electrospinning enclosure 300 and becollected by winding it onto a combination roller 210 (as shown in FIG.1). In other aspects illustrated in FIG. 10, however, the polymer fiberweb 110 may be stripped from the substrate 120 and wound onto a fiberweb roller 220 and the substrate wound onto a separate substratefinishing roller 230. In further aspects (not illustrated), thesubstrate may be a continuous substrate, and as the polymer fiber web isremoved from the substrate and wound onto a fiber web roller thesubstrate could be continuously cycled back into the apparatus 100 (inmuch the same manner that the plurality of continuous electrode wires1000 are operated continuously).

The substrate 120 is preferably a porous/permeable material that is bothlightweight and that will allow hot gases from the primary distributionmanifold 1690A and secondary distribution manifold 1690B to passtherethrough and dry the polymer fiber web 110. It should, however, havesufficient strength to be transported through the apparatus100/electrospinning enclosure 300 without tearing. Moreover, thesubstrate 120 may be any suitable material that can be wound onto therollers described herein and that will receive the polymer fibers formedduring the electrospinning process. The substrate 120 may include asubstrate tensioner 130 that provides tension to the substrate 120 as itexits the electrospinning enclosure 300. A substrate re-direction roller135 could be provided to alter the travelling direction of the substrate120 as it is unrolled from the substrate supply roller 200.

In some aspects the apparatus 100 may include an emission control box1800A through which the plurality of continuous electrode wires 1000pass before entering and after exiting the electrospinning enclosure300. The emission control box 1800A includes optimized gap spaces forthe plurality of continuous electrode wires 1000 so as to minimize entryof atmosphere/air proximate the electrospinning enclosure 300 into theelectrospinning enclosure 300 during operation of the apparatus 100.

In further aspects the apparatus 100 may include a wire scrubber 1900.The wire scrubber 1900 may be in contact with the plurality ofcontinuous electrode wires 1000 at some suitable location—such as alocation proximate to where the plurality of continuous electrode wires1000 enter the electrospinning enclosure (see FIG. 12)—and may providean additional mechanism to clean the surface of the plurality ofcontinuous electrode wires 1000. In certain aspects the wire scrubber islocated external to the electrospinning enclosure. In one aspect thewire scrubber is an abrasive material such as sandpaper. The wirescrubber 1900 physically contacts the plurality of continuous electrodewires 1000 and abrasively removes any deposited and/or coated polymerthat remains on the wire surface, thereby enhancing the efficiency ofthe electrode wire. Other wire scrubbing materials, and other abrasivematerials, are known and could be used in the wire scrubber 1900.

As shown in the figures, the apparatus 100 may include numerous pulleysP for maintaining and/or changing the direction of movement of one ormore of the plurality of continuous electrode wires 1000, the substrate120 and the polymer fiber web 110.

Aspects of the apparatus 100 described herein also provide substantialadvantages over conventional electrospinning processes by allowinglarge-scale industrial production of hundreds of kg/hr or more usingdozens or even hundreds of continuous electrode wires. In some aspectsthe apparatus could include over 25 continuous electrode wires, or over50 continuous electrode wires, or over 100 continuous electrode wires,or over 150 continuous electrode wires, or over 200 continuous electrodewires, or over 300 continuous electrode wires, or over 400 continuouselectrode wires, or even up to or over 500 continuous electrode wires.Moreover, the plurality of continuous electrode wires may have anextremely long length. Continuous electrode wire lengths of 5 meters (m)to even 50 m or more could be used in certain aspects of the disclosure,with continuous polymer fiber production rates that are not achievablein conventional systems that operate using batch systems.

Methods for Continuous Needleless Electrospinning of a Liquid PolymerSource into a Nanoscale or Submicron Scale Polymer Fiber Web

The present disclosure further relates to methods for continuousneedleless electrospinning of a liquid polymer source into a nanoscaleor submicron scale polymer fiber web. The methods incorporate componentsof the apparatus 100 described herein, the description and operation ofwhich will not be duplicated here, and the reference numbers for thesecomponents will be used when referring to their incorporation into themethods. With reference to FIG. 13, in one aspect the method 2000includes, at 2100, driving a plurality of continuous electrode wiresthrough an electrospinning enclosure including at least one liquidpolymer coating device and an electrospinning zone with a wire drivesystem located external to the electrospinning enclosure. Step 2200includes driving a substrate through the electrospinning enclosure andthe electrospinning zone substantially parallel to the plurality ofcontinuous electrode wires with a substrate conveyor system locatedexternal to the electrospinning enclosure. At step 2300 a layer ofliquid polymer is coated onto a surface of the plurality of continuouselectrode wires in the at least one liquid polymer coating device. Atstep 2400 nanoscale or submicron scale polymer fibers are formed in theelectrospinning zone from the liquid polymer coated onto the surface ofthe plurality of continuous electrode wires. Step 2500 includescollecting the nanoscale or submicron scale polymer fibers on thesubstrate as a polymer fiber web. At step 2600 residual polymer isremoved from the surface of the plurality of continuous electrode wiresusing a wire cleaning assembly located within the electrospinningenclosure.

Other aspects may be, but do not have to be, included in the method 2000described herein, including but not limited to: measuring the resistanceof one or more of the plurality of continuous electrode wires using aresistance measuring system 560; recycling liquid polymer and providingliquid polymer feed using a liquid polymer recycle and feed system 1200;preparing liquid polymer using a liquid polymer preparation system 1300;storing and supplying solvent using a solvent storage and supply system1400; collecting, scrubbing and/or cleaning vapors using a vaporcollection and solvent recovery system 1600; blowing draft gas onto theplurality of continuous electrode wires and/or drying gas/hot gas ontothe substrate/polymer fiber web as described above; using a substrateconveyor system 150 for moving the substrate through the electrospinningenclosure and winding the substrate and polymer fiber web (eitherseparately or in combination) onto rollers; using emission control boxes1800A, B, C to minimize entry of air into the electrospinning enclosure;and scrubbing the plurality of continuous electrode wires with a wirescrubber 1900.

Methods for Driving a Plurality of Continuous Electrode Wires Through anElectrospinning Apparatus

The present disclosure further relates to methods for driving aplurality of continuous electrode wires through an electrospinningapparatus. The methods incorporate components of the apparatus 100described herein, the description and operation of which will not beduplicated here, and the reference numbers for these components will beused when referring to their incorporation into the methods. Theelectrospinning apparatus 100 includes an electrospinning enclosure 300within which a nanoscale or submicron scale polymer fiber web 110 isformed onto a substrate 120 from a liquid polymer layer coated onto aplurality of continuous electrode wires 1000. With reference to FIG. 14,in some aspects the method 3000 includes, at 3100, arranging a pluralityof continuous electrode wires onto a master wire drive drum and a slavewire drive drum. Each of the master wire drive drum and the slave wiredrive drum include a plurality of wire guides, and each of the wireguides include a channel or groove for receiving one of the plurality ofcontinuous electrode wires. At step 3200 the master wire drive drum isrotated to drive the plurality of continuous electrode wires through theelectrospinning enclosure. The master wire drive drum and the slave wiredrive drum are external to the electrospinning apparatus.

Other aspects may be, but do not have to be, included in the method3000, including but not limited methods of operating those systems andcomponents described herein.

Methods for Collecting a Nanoscale or Submicron Scale Polymer Fiber Webfrom an Electrospinning Enclosure

The present disclosure further relates to methods for collecting ananoscale or submicron scale polymer fiber web from an electrospinningenclosure. The methods incorporate components of the apparatus 100described herein, the description and operation of which will not beduplicated here, and the reference numbers for these components will beused when referring to their incorporation into the methods. Theelectrospinning apparatus 100 includes an electrospinning enclosure 300and electrospinning zone Z within which the nanoscale or submicron scalepolymer fiber web 110 is formed onto a substrate 120 from a liquidpolymer layer coated onto a plurality of continuous electrode wires1000. With reference to FIG. 15, in some aspects the method 4000includes, at 4100, unrolling the substrate from a substrate supplyroller. At step 4200 the substrate is tensioned with a substratetensioner. The substrate is driven through the electrospinning enclosureand electrospinning zone substantially parallel to the plurality ofcontinuous electrode wires having the liquid polymer layer coatedthereon at 4300. At step 4400 nanoscale or submicron scale polymerfibers are electrospun from the liquid polymer layer coated onto theplurality of continuous electrode wires in the electrospinning zone. Thenanoscale or submicron scale polymer fibers are collected on thesubstrate as a polymer fiber web at step 4500. At step 4600 the polymerfiber web and the substrate are driven out of the electrospinningenclosure.

Other aspects may be, but do not have to be, included in the method4000, including but not limited methods of operating those systems andcomponents described herein.

Methods for Operating an Electrospinning Apparatus for ContinuousNeedleless Electrospinning a Nanoscale or Submicron Scale Polymer FiberWeb onto a Substrate

The present disclosure further relates to methods for operating anelectrospinning apparatus for continuous needleless electrospinning ananoscale or submicron scale polymer fiber web onto a substrate. Themethods incorporate components of the apparatus 100 described herein,the description and operation of which will not be duplicated here, andthe reference numbers for these components will be used when referringto their incorporation into the methods. The electrospinning apparatus100 includes an electrospinning enclosure 300 including at least oneliquid polymer coating device 400 and an electrospinning zone Z and awire drive system 600 located external to the electrospinning enclosure300. The wire drive system 600 drives a plurality of continuouselectrode wires 1000 through the electrospinning enclosure 300 and theat least one liquid polymer coating device 400 and electrospinning zoneZ located therein. With reference to FIG. 16, in some aspects the method5000 includes, at 5100, providing liquid polymer feed to the at leastone liquid polymer coating device with a liquid polymer recycle and feedsystem located external to the electrospinning enclosure. At step S200vapors generated in the electrospinning enclosure are collected andprocessed in a vapor collection and solvent recovery system locatedexternal to the electrospinning enclosure. The vapor collection andsolvent recovery system maintains a pressure in the electrospinningenclosure that is lower than atmospheric pressure.

Other aspects may be, but do not have to be, included in the method5000, including but not limited to methods of operating those systemsand components described herein.

Various combinations of elements of this disclosure are encompassed bythis disclosure, e.g., combinations of elements from dependent claimsthat depend upon the same independent claim.

EXAMPLES OF THE DISCLOSURE

In various aspects, the present disclosure pertains to and includes atleast the following examples.

Example 1

An apparatus for continuous needless electrospinning of a liquid polymersource into a nanoscale or submicron scale polymer fiber web, theapparatus comprising:

a. an electrospinning enclosure comprising:

-   -   one or more liquid polymer coating devices;    -   an electrospinning zone comprising an electrically conductive        ground plate; and    -   a wire cleaning assembly;

b. a wire drive system located external to the electrospinningenclosure;

c. a plurality of continuous electrode wires, the plurality ofcontinuous electrode wires being parallel to each other, engaged withthe wire drive system, and extending through the electrospinningenclosure and one or more liquid polymer coating devices locatedtherein;

d. a substrate conveyor system located external to the electrospinningenclosure; and

e. one or more high voltage power supply units, wherein

the one or more liquid polymer coating devices coat a layer of liquidpolymer onto a surface of the plurality of continuous electrode wires,

the one or more high voltage power supply units apply high voltage tothe plurality of continuous electrode wires and generate an electricalfield between the plurality of continuous electrode wires and theelectrically conductive ground plate in the electrospinning zone,forming nanoscale or submicron scale polymer fibers from the liquidpolymer coated onto the surface of the plurality of continuous electrodewires,

the wire cleaning assembly comprises a solvent for cleaning residualliquid polymer from the plurality of continuous electrode wires, and

the substrate conveyor system drives the substrate through theelectrospinning enclosure and collects the nanoscale or submicron scalepolymer fibers on the substrate as a polymer fiber web.

Example 2

The apparatus according to Example 1, further comprising at least oneliquid polymer coating manifold, wherein the at least one liquid polymercoating manifold feeds the liquid polymer to the one or more liquidpolymer coating devices.

Example 3

The apparatus according to Examples 1 or 2, further comprising a liquidpolymer recycle and feed system, wherein the liquid polymer recycle andfeed system receives overflow liquid polymer from and provides freshliquid polymer to the one or more liquid polymer coating devices.

Example 4

The apparatus according to Example 3, further comprising at least oneliquid polymer overflow reservoir, wherein the at least one liquidpolymer overflow reservoir receives overflow liquid polymer from the oneor more liquid polymer coating devices and returns the overflow liquidpolymer to the liquid polymer recycle and feed system.

Example 5

The apparatus according to any of Examples 1 to 4, further comprising adraft gas supply system comprising a draft gas source and a draft gasdistribution manifold, wherein the draft gas distribution manifoldreceives draft gas from the draft gas source and blows the draft gasonto the plurality of continuous electrode wires in the electrospinningzone to facilitate collection of the nanoscale or submicron scalepolymer fibers on the substrate.

Example 6

The apparatus according to any of Examples 1 to 5, further comprising aprimary drying region comprising a primary distribution manifold,wherein the primary distribution manifold distributes primary drying gasto the substrate and polymer fiber web formed thereon to facilitatedrying thereof.

Example 7

The apparatus according to Example 6, further comprising a secondarydrying region comprising a secondary distribution manifold, wherein thesecondary distribution manifold distributes secondary drying gas to thesubstrate and polymer fiber web formed thereon to facilitate dryingthereof

Example 8

The apparatus according to Example 7, wherein the secondary drying gashas a relatively lower solvent vapor content and a relatively highertemperature than the primary drying gas.

Example 9

The apparatus according to any of Examples 1 to 8, further comprising atleast one emission control box located proximate the electrospinningenclosure, the at least one emission control box comprising openings forone or more of the plurality of continuous electrode wires and substrateto enter or exit the electrospinning enclosure.

Example 10

The apparatus according to any of Examples 1 to 9 wherein the one ormore liquid polymer coating device comprises:

a liquid polymer coating manifold for coating a layer of liquid polymeron the surface of a plurality of continuous electrode wires, the liquidpolymer coating manifold comprising a plurality of wire inlet aperturesand a plurality of wire outlet apertures;

a liquid polymer overflow reservoir to receive liquid polymer overflowfrom the liquid polymer coating manifold; and

at least one set of wire positioning pulleys that guide the plurality ofcontinuous electrode wires through the plurality of wire inlet and wireoutlet apertures.

Example 11

The apparatus according to Example 10, wherein each of the plurality ofwire inlet apertures aligns with one of the plurality of wire outletapertures so as to allow one of the plurality of continuous electrodewires to pass therethrough.

Example 12

The apparatus according to Example 10 or 11, wherein each of theplurality of wire inlet apertures and the plurality of wire outletapertures comprises a capillary tube, wherein the capillary tube guidesthe continuous electrode wire through the liquid polymer coatingmanifold so as to allow the liquid polymer to coat the continuouselectrode wire within the liquid polymer coating manifold and minimizeleakage of liquid polymer out of the liquid polymer coating manifold.

Example 13

The apparatus according to any of Examples 10 to 12, wherein the liquidpolymer coating manifold comprises a liquid polymer supply port and aliquid polymer overflow port.

Example 14

The apparatus according to Example 13, wherein the liquid polymercoating device comprises a liquid polymer recirculation port and aliquid polymer overflow reservoir for receiving liquid polymer from theliquid polymer overflow port.

Example 15

The apparatus according to any of Examples 1 to 14, wherein the one ormore high voltage power supply units comprises:

a negative voltage source connected to the electrically conductiveground plate; and

a positive voltage source connected to at least one electricallyconductive freely rotating axle, wherein the at least one electricallyconductive freely rotating axle is in rotating contact with theplurality of continuous electrode wires.

Example 16

The apparatus according to Example 15, wherein the at least oneelectrically conductive freely rotating axle comprises a plurality ofgrooves corresponding to the number of continuous electrode wires, andeach of the grooves receives one of the continuous electrode wires andmaintains contact therewith so that high voltage from the one or morehigh voltage power supply units is passed to the continuous electrodewires.

Example 17

The apparatus according to any of Examples 1 to 16, wherein the one ormore high voltage power supply units is located within or outside theelectrospinning enclosure.

Example 18

The apparatus according to any of Examples 1 to 17, wherein the wirecleaning assembly comprises a solvent coating manifold for washing andremoving residual polymer solution from the surface of the plurality ofcontinuous electrode wires, the solvent coating manifold comprising:

a plurality of solvent manifold wire inlet apertures and a plurality ofsolvent manifold wire outlet apertures; and

a solvent overflow reservoir for receiving overflow solvent from thesolvent coating manifold.

Example 19

The apparatus according to Example 18, wherein each of the plurality ofsolvent manifold wire inlet apertures aligns with one of the pluralityof solvent manifold wire outlet apertures so as to allow one of theplurality of continuous electrode wires to pass therethrough.

Example 20

The apparatus according to any of Examples 1 to 19, wherein thesubstrate conveyor system comprises:

a combination roller for winding the substrate and electrospun polymerfiber web thereon; or

a fiber web roller for winding the electrospun polymer fiber web thereonand a substrate finishing roller for winding the substrate thereon.

Example 21

The apparatus according to any of Examples 1 to 20, wherein theapparatus further comprises a resistance measuring system comprising anupstream contact point and a downstream contact point located a distancedownstream of the plurality of continuous electrode wires, wherein

the resistance measuring system measures electrical resistance of one ormore of the plurality of continuous electrode wires between the upstreamcontact point and the downstream contact point, and

the measured electrical resistance provides an indication of solidpolymer remaining on the surface of the continuous electrode wire.

Example 22

The apparatus according to any of Examples 1 to 21, wherein theapparatus further comprises an electrode wire scrubber, wherein the wirescrubber is located external to the electrospinning enclosure andincludes an abrasive material that physically contacts the plurality ofcontinuous electrode wires to remove unwanted solid polymer therefrom.

Example 23

The apparatus according to any of Examples 1 to 22, wherein the liquidpolymer is a naturally occurring polymer or synthetic polymer and is ina melt liquid or polymer solution form.

Example 24

The apparatus according to Example 23, wherein the naturally occurringpolymer is a protein, cellulose, lignin, collagen, DNA, rubber, or acombination thereof.

Example 25

The apparatus according to Example 23, wherein the synthetic polymer isa polyamide, polyurethane, polybenzimidazole, polycarbonate,polyacrylonitrile, polyvinyl alcohol, polylactic acid,polyethylene-co-vinyl acetate, polymethacrylate, polyethylene oxide,polyaniline, polystyrene, polyvinylphenol, polyvinylchloride,polyetherimide, polyaramid, synthetic rubber, or a combination thereof.

Example 26

The apparatus according to any of Examples 1 to 25, wherein the liquidpolymer or solvent is flammable or toxic.

Example 27

The apparatus according to any of Examples 1 to 26, comprising aplurality of liquid polymer coating devices and a plurality of differenttypes of liquid polymers.

Example 28

The apparatus according to any of Examples 1 to 27, further comprising aliquid polymer preparation system for providing makeup liquid polymer tothe apparatus.

Example 29

The apparatus according to any of Examples 1 to 28, further comprising asolvent storage and supply system for storing and supplying solvent tothe apparatus.

Example 30

The apparatus according to any of Examples 1 to 29, further comprising avapor collection and solvent recovery system, wherein the vaporcollection and solvent recovery system maintains the electrospinningenclosure at a pressure less than atmospheric pressure and preventspotentially harmful vapors in the electrospinning enclosure fromescaping to the environment.

Example 31

A method for continuous needleless electrospinning of a liquid polymersource into a nanoscale or submicron scale polymer fiber web,comprising:

driving a plurality of continuous electrode wires through anelectrospinning enclosure comprising at least one liquid polymer coatingdevice and an electrospinning zone with a wire drive system locatedexternal to the electrospinning enclosure;

driving a substrate through the electrospinning enclosure and theelectrospinning zone substantially parallel to the plurality ofcontinuous electrode wires with a substrate conveyor system locatedexternal to the electrospinning enclosure;

coating a layer of liquid polymer onto a surface of the plurality ofcontinuous electrode wires in the at least one liquid polymer coatingdevice;

forming, in the electrospinning zone, nanoscale or submicron scalepolymer fibers from the liquid polymer coated onto the surface of theplurality of continuous electrode wires;

collecting the nanoscale or submicron scale polymer fibers on thesubstrate as a polymer fiber web; and

removing residual polymer from the surface of the plurality ofcontinuous electrode wires using a wire cleaning assembly located withinthe electrospinning enclosure.

Example 32

The method according to Example 31, further comprising drying thesubstrate and the polymer fiber web formed thereon in a primary dryingregion with primary drying gas.

Example 33

The method according to Example 32, further comprising drying thesubstrate and the polymer fiber web formed thereon in a secondary dryingregion with secondary drying gas.

Example 34

The method according to any of Examples 31 to 33, further comprisingmeasuring electrical resistance of a discrete length of at least one ofthe plurality of continuous electrode wires using a resistance measuringsystem so as to provide an indication of solid polymer remaining on thesurface of the continuous electrode wire.

Example 35

The method according to Example 34, further comprising scrubbing thecontinuous electrode wire with a wire scrubber to remove solid polymerremaining on the surface of the continuous electrode wire.

Example 36

The method according to any of Examples 31 to 35, further comprisingwinding the polymer fiber web and the substrate onto a combinationroller.

Example 37

The method according to any of Examples 31 to 35, further comprisingseparating the polymer fiber web from the substrate, winding the polymerfiber web onto a fiber web roller, and winding the substrate onto asubstrate finishing roller.

Each of these non-limiting examples can stand on its own, or can becombined in various permutations or combinations with one or more of theother examples.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific aspects in which the disclosurecan be practiced. These aspects are also referred to herein as“examples.” Such examples can include elements in addition to thoseshown or described. However, the present inventors also contemplateexamples in which only those elements shown or described are provided.Moreover, the present inventors also contemplate examples using anycombination or permutation of those elements shown or described (or oneor more aspects thereof), either with respect to a particular example(or one or more aspects thereof), or with respect to other examples (orone or more aspects thereof) shown or described herein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, in an example, the code can be tangiblystored on one or more volatile, non-transitory, or non-volatile tangiblecomputer-readable media, such as during execution or at other times.Examples of these tangible computer-readable media can include, but arenot limited to, hard disks, removable magnetic disks, removable opticaldisks (e.g., compact disks and digital video disks), magnetic cassettes,memory cards or sticks, random access memories (RAMs), read onlymemories (ROMs), and the like.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otheraspects can be used, such as by one of ordinary skill in the art uponreviewing the above description. The Abstract is provided to comply with37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the natureof the technical disclosure. It is submitted with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. Also, in the above Detailed Description, various features may begrouped together to streamline the disclosure. This should not beinterpreted as intending that an unclaimed disclosed feature isessential to any claim. Rather, inventive subject matter may lie in lessthan all features of a particular disclosed aspect. Thus, the followingclaims are hereby incorporated into the Detailed Description as examplesor aspects, with each claim standing on its own as a separate aspect,and it is contemplated that such aspects can be combined with each otherin various combinations or permutations. The scope of the disclosureshould be determined with reference to the appended claims, along withthe full scope of equivalents to which such claims are entitled.

1. An apparatus for continuous needleless electrospinning of a liquidpolymer source into a nanoscale or submicron scale polymer fiber web,the apparatus comprising: a. an electrospinning enclosure comprising:one or more liquid polymer coating devices; an electrospinning zonecomprising an electrically conductive ground plate; and a wire cleaningassembly; b. a wire drive system located external to the electrospinningenclosure; c. a plurality of continuous electrode wires, the pluralityof continuous electrode wires being parallel to each other, engaged withthe wire drive system, and extending through the electrospinningenclosure and one or more liquid polymer coating devices locatedtherein, wherein the one or more liquid polymer coating devices compriseat least one liquid polymer coating manifold, wherein the at least oneliquid polymer coating manifold feeds the liquid polymer to the one ormore liquid polymer coating devices; d. a substrate conveyor systemlocated external to the electrospinning enclosure; and e. one or morehigh voltage power supply units, wherein the one or more liquid polymercoating devices coat a layer of liquid polymer onto a surface of theplurality of continuous electrode wires, the one or more high voltagepower supply units apply high voltage to the plurality of continuouselectrode wires and generate an electrical field between the pluralityof continuous electrode wires and the electrically conductive groundplate in the electrospinning zone, forming nanoscale or submicron scalepolymer fibers from the liquid polymer coated onto the surface of theplurality of continuous electrode wires, the wire cleaning assemblycomprises a solvent for cleaning residual liquid polymer from theplurality of continuous electrode wires, and the substrate conveyorsystem drives a substrate through the electrospinning enclosure andcollects the nanoscale or submicron scale polymer fibers on thesubstrate as a polymer fiber web.
 2. (canceled)
 3. The apparatusaccording to claim 1, further comprising a liquid polymer recycle andfeed system, wherein the liquid polymer recycle and feed system receivesoverflow liquid polymer from and provides fresh liquid polymer to theone or more liquid polymer coating devices; and optionally at least oneliquid polymer overflow reservoir, wherein the at least one liquidpolymer overflow reservoir receives overflow liquid polymer from the oneor more liquid polymer coating devices and returns the overflow liquidpolymer to the liquid polymer recycle and feed system.
 4. (canceled) 5.The apparatus according to claim 1, further comprising a draft gassupply system comprising a draft gas source and a draft gas distributionmanifold, wherein the draft gas distribution manifold receives draft gasfrom the draft gas source and blows the draft gas onto the plurality ofcontinuous electrode wires in the electrospinning zone to facilitatecollection of the nanoscale or submicron scale polymer fibers on thesubstrate.
 6. The apparatus according to claim 1, further comprising aprimary drying region comprising a primary distribution manifold,wherein the primary distribution manifold distributes primary drying gasto the substrate and polymer fiber web formed thereon to facilitatedrying thereof.
 7. The apparatus according to claim 6, furthercomprising a secondary drying region comprising a secondary distributionmanifold, wherein the secondary distribution manifold distributessecondary drying gas to the substrate and polymer fiber web formedthereon to facilitate drying thereof.
 8. The apparatus according toclaim 1, further comprising at least one emission control box locatedproximate the electrospinning enclosure, the at least one emissioncontrol box comprising openings for one or more of the plurality ofcontinuous electrode wires and substrate to enter or exit theelectrospinning enclosure.
 9. The apparatus according to claim 1,wherein the at least one liquid polymer coating manifold for coating alayer of liquid polymer on the surface of the plurality of continuouselectrode wires comprises a plurality of wire inlet apertures and aplurality of wire outlet apertures; and wherein the one or more liquidpolymer coating device (400) further comprises: a liquid polymeroverflow reservoir to receive liquid polymer overflow from the at leastone liquid polymer coating manifold; and at least one set of wirepositioning pulleys that guide the plurality of continuous electrodewires through the plurality of wire inlet apertures and the plurality ofwire outlet apertures.
 10. The apparatus according to claim 9, whereineach of the plurality of wire inlet apertures aligns with one of theplurality of wire outlet apertures so as to allow one of the pluralityof continuous electrode wires to pass therethrough.
 11. The apparatusaccording to claim 9, wherein each of the plurality of wire inletapertures and the plurality of wire outlet apertures comprises acapillary tube, wherein the capillary tube guides the continuouselectrode wire through the at least one liquid polymer coating manifoldso as to allow the liquid polymer to coat the continuous electrode wirewithin the at least one liquid polymer coating manifold and minimizeleakage of liquid polymer out of the at least one liquid polymer coatingmanifold.
 12. The apparatus according to claim 9, wherein the at leastone liquid polymer coating manifold comprises a liquid polymer supplyport and a liquid polymer overflow port.
 13. The apparatus according toclaim 12, wherein the liquid polymer coating device comprises a liquidpolymer recirculation port and a liquid polymer overflow reservoir forreceiving liquid polymer from the liquid polymer overflow port.
 14. Theapparatus according to claim 1, wherein the one or more high voltagepower supply units comprises: a negative voltage source connected to theelectrically conductive ground plate; and a positive voltage sourceconnected to at least one electrically conductive freely rotating axle,wherein the at least one electrically conductive freely rotating axle isin rotating contact with the plurality of continuous electrode wires;and optionally wherein the at least one electrically conductive freelyrotating axle comprises a plurality of grooves corresponding to thenumber of continuous electrode wires (1000), and each of the groovesreceives one of the continuous electrode wires (1000) and maintainscontact therewith so that high voltage from the one or more high voltagepower supply units (820) is passed to the continuous electrode wires.15. (canceled)
 16. The apparatus according to claim 1, wherein thesubstrate conveyor system comprises: a combination roller for windingthe substrate and electrospun polymer fiber web thereon; or a fiber webroller for winding the electrospun polymer fiber web thereon and asubstrate finishing roller for winding the substrate thereon.
 17. Theapparatus according to claim 1, wherein the apparatus further comprisesa resistance measuring system comprising an upstream contact point and adownstream contact point located a distance downstream of the pluralityof continuous electrode wires, wherein the resistance measuring systemmeasures electrical resistance of one or more of the plurality ofcontinuous electrode wires between the upstream contact point and thedownstream contact point, and the measured electrical resistanceprovides an indication of solid polymer remaining on the surface of thecontinuous electrode wire.
 18. The apparatus according to claim 1,wherein the apparatus further comprises an electrode wire scrubber,wherein the wire scrubber is located external to the electrospinningenclosure and includes an abrasive material that physically contacts theplurality of continuous electrode wires to remove unwanted solid polymertherefrom.
 19. The apparatus according to claim 1, wherein the liquidpolymer or solvent is flammable or toxic.
 20. A method for continuousneedleless electrospinning of a liquid polymer source into a nanoscaleor submicron scale polymer fiber web, comprising: driving a plurality ofcontinuous electrode wires through an electrospinning enclosurecomprising at least one liquid polymer coating device and anelectrospinning zone with a wire drive system located external to theelectrospinning enclosure; driving a substrate through theelectrospinning enclosure and the electrospinning zone substantiallyparallel to the plurality of continuous electrode wires with a substrateconveyor system located external to the electrospinning enclosure;coating a layer of liquid polymer onto a surface of the plurality ofcontinuous electrode wires in the at least one liquid polymer coatingdevice, wherein the at least one liquid polymer coating device comprisesat least one liquid polymer coating manifold, wherein the at least oneliquid polymer coating manifold feeds the liquid polymer to the at leastone liquid polymer coating device; forming, in the electrospinning zone,nanoscale or submicron scale polymer fibers from the liquid polymercoated onto the surface of the plurality of continuous electrode wires;collecting the nanoscale or submicron scale polymer fibers on thesubstrate as a polymer fiber web; and removing residual polymer from thesurface of the plurality of continuous electrode wires using a wirecleaning assembly located within the electrospinning enclosure.
 21. Theapparatus according to claim 1, further comprising a vapor collectionand solvent recovery system to collect vapors from the electrospinningenclosure, wherein the solvent for cleaning residual liquid polymer fromthe plurality of continuous electrode wires comprises solvent recoveredin the vapor collection and solvent recovery system.
 22. The apparatusaccording to claim 1, wherein the wire cleaning assembly furthercomprises a solvent coating manifold that includes a number of solventmanifold wire inlet apertures and solvent manifold wire outletapertures.
 23. The apparatus according to claim 22, wherein the wirecleaning assembly further comprises: a solvent coating port to supplysolvent; a solvent overflow reservoir that receives overflow solventfrom the solvent manifold wire inlet apertures and solvent manifold wireoutlet apertures; and a solvent recirculation port to return solventcollected in the solvent overflow reservoir to a solvent storage andsupply system.